def groupbyhead(items,headsize=1):
'''
groupbyhead(items,headsize=1)
=============================
Group a list of items according to the starting character(s) of items.
Return a dictionary.
:Author: Runsun Pan
:Date: 1/1/06
:Required: Raymond Hettinger's groupby class
http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/259173
Usage
-----
::
>>> states = ['Alaska','Arizona','Arkansas','California','Colorado',
'Connecticut','Georgia','Idaho','Illinois','Indiana','Iowa','Kansas',
'Kentucky','Maine','Maryland', 'Michigan','Minnesota','Missouri','Montana']
>>> x= groupbyhead(states)
>>> print prndict(x, sortkey=1) #
{
'A':['Alaska', 'Arizona', 'Arkansas'],
'C':['California', 'Colorado', 'Connecticut'],
'G':['Georgia'],
'I':['Idaho', 'Illinois', 'Indiana', 'Iowa'],
'K':['Kansas', 'Kentucky'],
'M':['Maine', 'Maryland', 'Michigan', 'Minnesota', 'Missouri', 'Montana']
}
>>> x= groupbyhead(states,2)
>>> print prndict(x, sortkey=1) #
{
'Al':['Alaska'],
'Ar':['Arizona', 'Arkansas'],
'Ca':['California'],
'Co':['Colorado', 'Connecticut'],
'Ge':['Georgia'],
'Id':['Idaho'],
'Il':['Illinois'],
'In':['Indiana'],
'Io':['Iowa'],
'Ka':['Kansas'],
'Ke':['Kentucky'],
'Ma':['Maine', 'Maryland'],
'Mi':['Michigan', 'Minnesota', 'Missouri'],
'Mo':['Montana']
}
# prndict: http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/327142
'''
return dict( [(k,g) for k, g in groupby(items, key=lambda x:x[0:headsize])] )
